Magneto-transport of high TCR (temperature coefficient of resistance) La2/3Ca1/3MnO3 : Ag polycrystalline composites

We report the synthesis, (micro)structure, magneto-transport and magnetization of polycrystalline La2/3Ca1/3MnO3:Agx composites with x=0.0x=0.0, 0.1, 0.2, 0.3 and 0.4. The temperature coefficient of resistance (TCR) near ferromagnetic (FM) transition is increased significantly with the addition of Ag. The FM   transition temperature (TFM) is also increased slightly with Ag addition. Magneto-transport measurements revealed that magneto-resistance MR   is found to be maximum near TFM. Further the increased MR of up to 60% is seen above 300 K for higher silver added samples in an applied field of 7 T. Sharp TCR   is seen near TFM with the highest value of up to 15% for Ag(0.4) sample, which is an order of magnitude higher than the present pristine sample and the best value yet reported for any polycrystalline LCMO compound. Increased TCR  , TFM and significant above room temperature MR of La2/3Ca1/3MnO3:Agx composites is explained on the basis of improved grain size and connectivity with silver addition in the matrix. Better coupled FM domains and nearly conducting grain boundaries give rise to improved physical properties of the La2/3Ca1/3MnO3 manganites.